CN114759056A - Method for manufacturing image sensing device comprising photodiode - Google Patents
Method for manufacturing image sensing device comprising photodiode Download PDFInfo
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- CN114759056A CN114759056A CN202210535987.1A CN202210535987A CN114759056A CN 114759056 A CN114759056 A CN 114759056A CN 202210535987 A CN202210535987 A CN 202210535987A CN 114759056 A CN114759056 A CN 114759056A
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- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 23
- 229910052732 germanium Inorganic materials 0.000 claims abstract description 82
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims abstract description 82
- 230000009969 flowable effect Effects 0.000 claims abstract description 54
- 239000003989 dielectric material Substances 0.000 claims abstract description 52
- 238000005468 ion implantation Methods 0.000 claims abstract description 43
- 238000002955 isolation Methods 0.000 claims abstract description 40
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000001257 hydrogen Substances 0.000 claims abstract description 25
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 25
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 22
- 239000010703 silicon Substances 0.000 claims abstract description 22
- 238000005498 polishing Methods 0.000 claims abstract description 10
- 238000011049 filling Methods 0.000 claims abstract description 5
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 claims description 21
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 18
- 238000002513 implantation Methods 0.000 claims description 16
- 229920003209 poly(hydridosilsesquioxane) Polymers 0.000 claims description 10
- 238000000137 annealing Methods 0.000 claims description 6
- 239000004642 Polyimide Substances 0.000 claims description 4
- 229920001721 polyimide Polymers 0.000 claims description 4
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 4
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 3
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 3
- 238000005229 chemical vapour deposition Methods 0.000 claims description 3
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 claims description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 3
- 238000002347 injection Methods 0.000 abstract description 11
- 239000007924 injection Substances 0.000 abstract description 11
- 239000010410 layer Substances 0.000 description 76
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 7
- 235000012239 silicon dioxide Nutrition 0.000 description 7
- 239000000377 silicon dioxide Substances 0.000 description 7
- 239000002184 metal Substances 0.000 description 6
- 150000002500 ions Chemical class 0.000 description 3
- 239000011241 protective layer Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
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- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 2
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- 239000004065 semiconductor Substances 0.000 description 2
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- 208000010415 Low Vision Diseases 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000005234 chemical deposition Methods 0.000 description 1
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- 229910044991 metal oxide Inorganic materials 0.000 description 1
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14643—Photodiode arrays; MOS imagers
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Abstract
The invention discloses a method for manufacturing an image sensing device comprising a photodiode, which comprises the following steps: forming an isolation channel on the front side of the germanium donor wafer; filling the isolation trenches with a flowable dielectric material; forming a PIN photodiode; removing the remaining flowable dielectric material; forming a hydrogen injection layer; providing a silicon circuit wafer, and connecting the PIN photodiode layer with the silicon circuit wafer through an interconnection layer; and polishing the cut germanium layer by peeling the hydrogen implanted layer to separate the PIN photodiode layer from the germanium donor wafer. By adopting the flowable dielectric material to divide the photodiode array area, the ideal photodiode can be formed in the photodiode array area by combining the ion implantation which can accurately control the doping parameters, the process flow is simple, and the process parameters can be accurately controlled.
Description
Technical Field
The invention belongs to the technical field of semiconductor device manufacturing, and particularly relates to a manufacturing method of an image sensing device comprising a photodiode.
Background
Image sensors are increasingly used in the fields of the automotive industry, engineering machinery, agriculture, and life sciences. Compared with a visible light sensing image sensor, a Short-wave Infrared (SWIR) image sensor has better penetrability and higher sensitivity in low-vision environments such as night vision and foggy days.
The spectral response of silicon sensors is limited to wavelengths within 1 μm, which has low light absorption efficiency in the near infrared spectrum. The germanium sensor has better optical response in the range of 0.4-1.6 μm. This has led to a number of studies on silicon-based germanium (Ge-on-Si) short-wave infrared image sensors.
The epitaxial growth method is an existing method for manufacturing silicon-based germanium, namely, a germanium layer is directly grown on a silicon substrate. However, because the lattice mismatch between silicon and germanium is 4.2% (lattice mismatch), the accumulation of mismatch energy can generate defects such as misfit dislocation (mismatching) and threading dislocation (threading dislocation) at the interface between the two. In order to suppress such defects, it is necessary to increase the complexity of the manufacturing process thereof (for example, selective growth using narrow apertures).
Moreover, the photodiode is an important part of the image sensor, and how to form an ideal photodiode in the process of manufacturing silicon-based germanium also becomes an important factor influencing the quality of the image sensor.
Disclosure of Invention
Based on the problems in the prior art, the invention provides a manufacturing method of an image sensing device comprising a photodiode, which solves and overcomes the technical problems that dislocation is generated and the process complexity is higher when silicon-based germanium is manufactured by an epitaxial growth method in the prior art; the invention relates to a manufacturing method of an image sensing device, which has simple process and no lattice mismatch and can form a high-quality photodiode.
According to the technical scheme, the invention provides a manufacturing method of an image sensing device comprising a photodiode, wherein isolation channels are formed on the front side of a germanium donor wafer, and adjacent isolation channels limit an array region of a PIN photodiode; the method comprises the steps of dividing a photodiode array area by adopting a flowable dielectric material, and forming a required photodiode in the photodiode array area by combining ion implantation for accurately controlling doping parameters; the array area defining the PIN photodiode is a pixel area of the image sensing device.
Specifically, the method for manufacturing the image sensing device comprising the photodiode comprises the following steps:
s1: providing a germanium donor wafer;
s2: forming isolation channels on the front side of the germanium donor wafer, wherein the adjacent isolation channels define an array region of the PIN photodiode;
S3: filling the isolation trenches with a flowable dielectric material to fill the isolation trenches with the flowable dielectric material and to cover the front side of the germanium donor wafer with the flowable dielectric material;
s4: thinning the flowable dielectric material covering the front side of the germanium donor wafer;
s5: forming a first mask on the front surface of the germanium donor wafer in the array region, wherein the region which is not covered by the first mask is a first open region; performing first conductive type ion implantation on the first open region to form a first conductive type doped region in the front surface of the germanium donor wafer corresponding to the first open region, removing the first mask and annealing;
s6: forming a second mask on the front surface of the germanium donor wafer, wherein the area which is not covered by the second mask is a second open area; and performing second conductive type ion implantation on the second open region to form a second conductive type doping region in the front surface of the germanium donor wafer corresponding to the second open region, removing the second mask and annealing, wherein the first open region and the second open region are not overlapped completely, and the first conductive type doping region, the second conductive type doping region and the intrinsic region between the first conductive type doping region and the second conductive type doping region jointly form the PIN photodiode.
Further, the method for manufacturing an image sensing device including a photodiode further includes the following steps, after step S6:
s7: removing the remaining flowable dielectric material overlying the front side of the germanium donor wafer and polishing the front side of the germanium donor wafer;
s8: performing hydrogen ion implantation on the front surface of the germanium donor wafer to form a hydrogen implantation layer in the germanium donor wafer below the PIN photodiode, wherein the depth of the hydrogen implantation layer is greater than or equal to that of the isolation channel, and the PIN photodiode and the germanium layer between the hydrogen implantation layer and the PIN photodiode jointly form a PIN photodiode layer;
s9: providing a silicon circuit wafer comprising circuitry for controlling and reading the PIN photodiodes, with the PIN photodiode layer being connected to the silicon circuit wafer via an interconnect layer;
s10: and polishing the cut germanium layer by peeling the hydrogen implanted layer to separate the PIN photodiode layer from the germanium donor wafer.
Preferably, the flowable dielectric material is flowable silicon oxide or silicon nitride.
Preferably, the thickness of the photodiode layer (the subsequently transferred germanium transfer layer) ranges from 0.5 μm to 10 μm; the height of the isolation channel extends up to the depth of the photodiode layer (germanium transport layer). The isolation channel width may be 0.05 μm to 2 μm.
The isolation channels are used to divide the pixels, the size of the pixels/photodiodes being for example a square of 5 μm by 5 μm size. The pixels/photodiodes may have other shapes or sizes, e.g., rectangular, hexagonal, circular, etc. The minimum dimensions of the various features, including the pixel and photodiode dimensions, may be limited only by process tolerances.
Preferably, the flowable Dielectric material is formed by SOD (Spin-on Dielectric) or by low temperature plasma chemical vapor deposition in step S3.
Preferably, the SOD is silicate, siloxane, Methylsilsesquioxane (MSQ), Hydrogen Silsesquioxane (HSQ), MSQ/HSQ (Methyl Silsesquioxane/Hydrogen Silsesquioxane), perhydrosilazane, perhydropolysilazane, or polyimide.
Preferably, the thickness of the flowable dielectric material covering the front side of the ge donor wafer in step S3 is 1 μm to 3 μm.
Preferably, the flowable dielectric material overlying the front side of the ge donor wafer is completely removed in step S4.
Preferably, in step S4, the flowable dielectric material covering the front side of the ge donor wafer is thinned by CMP (chemical mechanical polishing/grinding), and the thickness of the thinned flowable dielectric material is 10nm to 100 nm.
Preferably, the first conductive type ion implantation and the second conductive type ion implantation have a dose of 1 × 1019atoms/cm3～1×1021atoms/cm3Of course, the process parameters and energy of the ion implantation may vary depending on the target dose range. Wherein the width of the intrinsic region ranges from 100nm (0.1 μm) to 3 μm, and the widths of the first-conductivity-type doped region and the second-conductivity-type doped region range from 1 μm to 2.45 μm.
Preferably, the dosage of the hydrogen ion implantation is 1 × 1015atoms/cm2～1×1018atoms/cm2(ii) a Preferably, the dose of the hydrogen ion implantation is at least 1 × 1016atoms/cm2；
And/or the energy range of hydrogen ion implantation is 1 keV-1 MeV;
and/or the execution temperature range of the hydrogen ion implantation is between room temperature and 600 ℃; preferably, the hydrogen ion implantation is performed at a temperature ranging from room temperature to 400 ℃;
and/or the depth precision of the hydrogen injection layer is +/-0.03 mu m to +/-0.05 mu m.
Preferably, the step S8 further includes: forming an injection protection layer on the front side of the germanium donor wafer through PECVD (plasma enhanced chemical vapor deposition), wherein the injection protection layer is a silicon dioxide layer; and removing the implantation protection layer after the hydrogen ion implantation is completed.
Preferably, 10nm to 90nm of silicon dioxide is formed as the implantation protection layer by PECVD, and the silicon dioxide is removed by dilute HF or buffered oxide etching.
Preferably, the interconnects in the interconnect layer are metal interconnects.
Preferably, the hydrogen injection layer is cut by the pulse of the energy source in step S10, and the energy source is a heat source, a cold source or a mechanical force source.
Preferably, the roughness of the surface cut in step S10 is less than 60 nm.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
Compared with the prior art, the invention has the positive improvement effects that: by adopting the flowable dielectric material to divide the photodiode array area, the ideal photodiode can be formed in the photodiode array area by combining the ion implantation which can accurately control the doping parameters, the process flow is simple, and the process parameters can be accurately controlled.
In addition, by introducing the interconnection layer and hydrogen ion implantation, the combination of silicon and germanium is facilitated, and the bubble layer formed in the germanium layer in turn makes the transfer of the PIN layer easy. The method has simple process steps and can not cause lattice mismatch.
Drawings
Fig. 1 to 11 are process flow diagrams of a method for manufacturing an image sensor device including a photodiode according to an embodiment of the present invention.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
The invention provides a method for manufacturing an image sensing device comprising a photodiode, wherein isolation channels are formed on the front surface of a germanium donor wafer, and the adjacent isolation channels limit an array region of a PIN photodiode; dividing a photodiode array region by using a flowable dielectric material, and forming a required photodiode in the photodiode array region by combining ion implantation for accurately controlling doping parameters; the array area defining the PIN photodiode is the pixel area of the image sensing device.
In detail, the invention relates to a method for manufacturing an image sensing device comprising a photodiode, wherein an isolation channel is formed on the front surface of a germanium donor wafer; filling the isolation trenches with a flowable dielectric material; forming a PIN photodiode; removing the remaining flowable dielectric material; forming a hydrogen injection layer; providing a silicon circuit wafer, and connecting the PIN photodiode layer with the silicon circuit wafer through an interconnection layer; and polishing the cut germanium layer by peeling the hydrogen implanted layer to separate the PIN photodiode layer from the germanium donor wafer. By adopting the flowable dielectric material to divide the photodiode array area, the ideal photodiode can be formed in the photodiode array area by combining the ion implantation which can accurately control the doping parameters, the process flow is simple, and the process parameters can be accurately controlled.
Specifically, the method for manufacturing the image sensing device comprising the photodiode comprises the following steps:
s1: providing a germanium donor wafer;
s2: forming isolation channels on the front side of the germanium donor wafer, wherein the adjacent isolation channels define an array region of the PIN photodiode;
s3: filling the isolation trenches with a flowable dielectric material to fill the isolation trenches with the flowable dielectric material and to cover the front side of the germanium donor wafer with the flowable dielectric material;
s4: thinning the flowable dielectric material covering the front side of the germanium donor wafer;
s5: forming a first mask on the front surface of the germanium donor wafer in the array region, wherein the region which is not covered by the first mask is a first open region; performing first conductive type ion implantation on the first open region to form a first conductive type doped region in the front surface of the germanium donor wafer corresponding to the first open region, removing the first mask and annealing;
s6: forming a second mask on the front surface of the germanium donor wafer, wherein the area which is not covered by the second mask is a second open area; and performing second conductive type ion implantation on the second open region to form a second conductive type doped region in the front surface of the germanium donor wafer corresponding to the second open region, removing the second mask and annealing, wherein the first open region and the second open region are not overlapped completely, and the first conductive type doped region, the second conductive type doped region and the intrinsic region between the first conductive type doped region and the second conductive type doped region jointly form the PIN photodiode.
Further, the method for manufacturing an image sensing device including a photodiode further includes the following step, after step S6:
s7: removing the residual flowable dielectric material covering the front side of the germanium donor wafer and polishing the front side of the germanium donor wafer;
s8: performing hydrogen ion implantation on the front side of the germanium donor wafer to form a hydrogen implantation layer in the germanium donor wafer below the PIN photodiode, wherein the depth of the hydrogen implantation layer is greater than or equal to that of the isolation channel, and the PIN photodiode and a germanium layer between the hydrogen implantation layer and the PIN photodiode jointly form a PIN photodiode layer;
s9: providing a silicon circuit wafer comprising circuitry for controlling and reading the PIN photodiodes, the PIN photodiode layer being connected to the silicon circuit wafer via an interconnect layer;
s10: and polishing the cut germanium layer by peeling the hydrogen implanted layer to separate the PIN photodiode layer from the germanium donor wafer.
Preferably, the flowable dielectric material is flowable silicon oxide or silicon nitride.
Preferably, the thickness of the photodiode layer (the subsequently transferred germanium transfer layer) ranges from 0.5 μm to 10 μm; the height of the isolation channel extends up to the depth of the photodiode layer (germanium transport layer). The isolation channel width may be 0.05 μm to 2 μm.
The isolation channels are used to divide the pixels, the size of the pixels/photodiodes being for example a square of 5 μm by 5 μm size. The pixels/photodiodes may have other shapes or sizes, e.g., rectangular, hexagonal, circular, etc. The minimum dimensions of the various features, including the pixel and photodiode dimensions, may be limited only by process tolerances.
Preferably, the flowable Dielectric material is formed by SOD (Spin-on Dielectric) or by low temperature plasma chemical vapor deposition in step S3.
Preferably, the SOD is silicate, siloxane, Methylsilsesquioxane (MSQ), Hydrogen Silsesquioxane (HSQ), MSQ/HSQ (Methyl Silsesquioxane/Hydrogen Silsesquioxane), perhydrosilazane, perhydropolysilazane, or polyimide.
Preferably, the thickness of the flowable dielectric material covering the front side of the ge donor wafer in step S3 is 1 μm to 3 μm.
Preferably, the flowable dielectric material overlying the front side of the ge donor wafer is completely removed in step S4.
Preferably, in step S4, the flowable dielectric material covering the front surface of the ge donor wafer is thinned by CMP (chemical mechanical polishing/grinding process), and the thickness of the thinned flowable dielectric material is 10nm to 100 nm.
Preferably, the first conductive type ion implantation and the second conductive type ion implantation have a dose of 1 × 1019atoms/cm3～1×1021atoms/cm3Of course, the process parameters and energy of the ion implantation may vary depending on the target dose range. Wherein the width of the intrinsic region is in the range of 100nm (0.1 μm) to 3 μm, and the widths of the first conductive type doped region and the second conductive type doped region are in the range of 1 μm to 2.45 μm.
Preferably, the dose of the hydrogen ion implantation is 1 × 1015atoms/cm2～1×1018atoms/cm2(ii) a Preferably, the dose of the hydrogen ion implantation is at least 1 × 1016atoms/cm2；
And/or the energy range of hydrogen ion implantation is 1 keV-1 MeV;
and/or, the execution temperature range of the hydrogen ion implantation is between room temperature and 600 ℃; preferably, the hydrogen ion implantation is performed at a temperature ranging from room temperature to 400 ℃;
and/or the depth precision of the hydrogen injection layer is +/-0.03 mu m to +/-0.05 mu m.
Preferably, the step S8 further includes: forming an injection protective layer on the front surface of the germanium donor wafer by PECVD (plasma enhanced chemical vapor deposition), wherein the injection protective layer is a silicon dioxide layer; and removing the implantation protection layer after the hydrogen ion implantation is completed.
Preferably, 10nm to 90nm of silicon dioxide is formed as the implantation protection layer by PECVD, and the silicon dioxide is removed by dilute HF or buffered oxide etching.
Preferably, the interconnects in the interconnect layer are metal interconnects.
Preferably, the hydrogen injection layer is cut by the pulse of the energy source in step S10, and the energy source is a heat source, a cold source or a mechanical force source.
Preferably, the roughness of the surface cut in step S10 is less than 60 nm.
A method for fabricating an image sensor device including a photodiode according to an embodiment of the present invention is described below with reference to fig. 1 to 11, taking a CMOS (complementary metal oxide semiconductor) image sensor as an example.
Referring to fig. 1, a germanium donor wafer 1 is provided and its surface polished.
Referring to fig. 2, isolation trenches 20 are formed in the front side of the germanium donor wafer 1 adjacent to which define the array region of the PIN photodiodes, i.e., the pixel region of the image sensing device. In the present embodiment, square pixels are taken as an example, for example, each pixel is a square of 5 μm × 5 μm, i.e., the isolation channel divides the front side of the germanium donor wafer 1 into a plurality of square regions of 5 μm × 5 μm, each for forming a photodiode. Wherein the width of the isolation channel ranges from 0.05 μm to 2 μm, for example, and the depth of the isolation channel ranges from 0.5 μm to 10 μm, for example. Fig. 2 here shows a schematic view of only one single pixel in a pixel area, the entire array area containing a plurality of similar pixels, by way of example only.
Still referring to fig. 2, the isolation trenches 20 are filled with a flowable dielectric material 2 to fill the isolation trenches with the flowable dielectric material and to cover the front side of the germanium donor wafer with the flowable dielectric material, e.g., the thickness of the flowable dielectric material covering the front side of the germanium donor wafer is 1 μm to 3 μm.
In particular, a portion of the front side of the germanium donor wafer 1 may be removed first by, for example, reactive ion etching to form isolation trenches, followed by low temperature chemical deposition to fill the isolation trenches with flowable silicon oxide.
In another preferred embodiment, the flowable Dielectric material can also be formed by Spin-on Dielectric (SOD), such as by Spin coating with polyimide.
Referring to fig. 3, the flowable dielectric material 2 covering the front side of the ge donor wafer is thinned by CMP to a thickness of 10nm to 100 nm.
Referring next to fig. 4-5, in the array region, a first mask 31 (e.g., photoresist) is formed on the front side of the ge donor wafer, and the region not covered by the first mask 31 is a first open region 41; a first conductivity type ion implantation (e.g., P + ions) is performed on the first open region to form a first conductivity type doped region 51 (N-type doped region) in the front side of the germanium donor wafer corresponding to the first open region, the first mask is removed and the wafer is annealed. The ion implantation dosage is 1 × 10 20atoms/cm3The width of the first open region 41 is, for example, 1 μm to 2.45 μm.
Referring to fig. 6-7, a second mask 32 (e.g., photoresist) is formed on the front side of the ge donor wafer, and the area not covered by the second mask 32 is a second open area 42; a second conductive type ion (B + ion) implantation is performed to the second open region to form a second conductive type doped region 52 (P-type doped region) in the front side of the germanium donor wafer corresponding to the second open region, the second mask is removed and annealed, wherein the first open region 41 and the second open region 42 are not overlapped at all, and the first conductive type doped region 51, the second conductive type doped region 52 and the intrinsic region 10 between the first conductive type doped region and the second conductive type doped region together constitute a PIN photodiode. Wherein the dosage of the ion implantation is 1 × 1020atoms/cm3The second open region 42 has a width of, for example, 1 μm to 2.45 μm. The width of the intrinsic region ranges, for example, from 0.1 μm to 3 μm. The process parameters and energy of the ion implantation may vary depending on the target dose range.
Referring next to fig. 8, the remaining flowable dielectric material overlying the front side of the ge donor wafer is removed and the front side of the ge donor wafer is polished.
Referring to fig. 9, an implantation protection layer (not shown) is formed on the front side of the germanium donor wafer by PECVD, the implantation protection layer being a silicon dioxide layer. Then at room temperature to germaniumThe front side of the donor wafer 1 is subjected to hydrogen ion implantation to form a hydrogen implanted layer 6 in the germanium donor wafer below the PIN photodiode, the depth of the hydrogen implanted layer 6 is greater than or equal to the depth of the isolation channel 20, and the PIN photodiode and the germanium layer between the hydrogen implanted layer and the PIN photodiode together form a PIN photodiode layer. Wherein the dosage of hydrogen ion implantation is 1 × 1015atoms/cm2～1×1018atoms/cm2(ii) a The energy range of hydrogen ion implantation is 1 keV-1 MeV; the depth accuracy of the hydrogen injection layer is + -0.03 μm to + -0.05 μm. And removing the implanted protective layer after the hydrogen ion implantation is finished.
Referring to fig. 10, a silicon circuit wafer 8 comprising circuitry for controlling and reading the PIN photodiodes is provided, with the PIN photodiode layer connected to the silicon circuit wafer 8 by means of an interconnect layer 7, wherein the interconnect layer may be made of two parts, for example an interconnect layer arranged on the PIN photodiode layer and another interconnect layer arranged on the silicon circuit wafer, the connection of the PIN photodiode layer and the silicon circuit wafer being made by the connection of the two interconnect layers. Wherein the interconnects in the interconnect layer are metal interconnects and the dielectric material insulates the metal interconnects (i.e., separate "metal lines").
Referring to fig. 11, the diced germanium layer is polished by separating the PIN photodiode layer from the germanium donor wafer 1 by peeling the hydrogen implanted layer. Wherein the interconnect layer provides inter-metal interconnects and dielectric material interconnects. In this embodiment, the hydrogen-implanted layer is cut by a pulse of an energy source, such as a heat source, a heat sink, or a mechanical force source. Wherein the roughness of the cleaved surface is less than 60 nm.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that these are by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.
Claims (10)
1. A method for manufacturing an image sensing device comprising a photodiode is characterized in that isolation channels are formed on the front side of a germanium donor wafer, and adjacent isolation channels define an array region of a PIN photodiode; dividing a photodiode array region by using a flowable dielectric material, and forming a required photodiode in the photodiode array region by combining ion implantation for accurately controlling doping parameters; the array area defining the PIN photodiode is the pixel area of the image sensing device.
2. The method of manufacturing according to claim 1, wherein the method of manufacturing the image sensing device including the photodiode includes the steps of:
s1: providing a germanium donor wafer;
s2: forming isolation channels on the front side of the germanium donor wafer, wherein the adjacent isolation channels define an array region of the PIN photodiode;
s3: filling the isolation trenches with a flowable dielectric material to fill the isolation trenches with the flowable dielectric material and to cover the front side of the germanium donor wafer with the flowable dielectric material;
s4: thinning the flowable dielectric material covering the front side of the germanium donor wafer;
s5: forming a first mask on the front surface of the germanium donor wafer in the array region, wherein the region which is not covered by the first mask is a first open region; performing first conductive type ion implantation on the first open region to form a first conductive type doped region in the front surface of the germanium donor wafer corresponding to the first open region, removing the first mask and annealing;
s6: forming a second mask on the front surface of the germanium donor wafer, wherein the area which is not covered by the second mask is a second open area; and performing second conductive type ion implantation on the second open region to form a second conductive type doped region in the front surface of the germanium donor wafer corresponding to the second open region, removing the second mask and annealing, wherein the first open region and the second open region are not overlapped completely, and the first conductive type doped region, the second conductive type doped region and the intrinsic region between the first conductive type doped region and the second conductive type doped region jointly form the PIN photodiode.
3. The method of manufacturing an image sensing device according to claim 2, wherein the method of manufacturing an image sensing device including a photodiode further includes the step of, after the step of S6:
s7: removing the residual flowable dielectric material covering the front side of the germanium donor wafer and polishing the front side of the germanium donor wafer;
s8: performing hydrogen ion implantation on the front surface of the germanium donor wafer to form a hydrogen implantation layer in the germanium donor wafer below the PIN photodiode, wherein the depth of the hydrogen implantation layer is greater than or equal to that of the isolation channel, and the PIN photodiode and the germanium layer between the hydrogen implantation layer and the PIN photodiode jointly form a PIN photodiode layer;
s9: providing a silicon circuit wafer comprising circuitry for controlling and reading the PIN photodiodes, with the PIN photodiode layer being connected to the silicon circuit wafer via an interconnect layer;
s10: and polishing the cut germanium layer by peeling the hydrogen implanted layer to separate the PIN photodiode layer from the germanium donor wafer.
4. The method of claim 2, wherein the flowable dielectric material is a flowable silicon oxide or silicon nitride.
5. The method of claim 2, wherein the flowable dielectric material is formed by SOD or by low temperature plasma chemical vapor deposition in step S3.
6. The method according to claim 5, wherein the SOD is silicate, siloxane, methylsilsesquioxane, hydrogen silsesquioxane, MSQ/HSQ, perhydrosilazane, perhydropolysilazane, or polyimide.
7. The method of claim 2, wherein the thickness of the front side flowable dielectric material overlying the ge donor wafer in step S3 is between 1 μm and 3 μm.
8. The method of claim 2 wherein the step S4 is performed by completely removing the flowable dielectric material covering the front side of the ge donor wafer.
9. The method of claim 2, wherein the step S4 is performed by CMP to thin the flowable dielectric material on the front side of the ge donor wafer, wherein the thickness of the thinned flowable dielectric material is 10nm to 100 nm.
10. The method of claim 1, wherein the hydrogen ion implantation is performed at a dose of 1 x 1015atoms/cm2～1×1018atoms/cm2。
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